Solve for $z$ : $30 + z = -28$
Subtract $30$ from both sides: $ \begin{eqnarray} \\ 30 + z &=& -28 \\ \\ {-30} && {-30} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{30 + z} &\hphantom{=}& \hphantom{-28} \\ z &=& -28 {- 30} \\ \end{eqnarray} $ Simplify. $ z = -58$